1. Field of the Invention
This invention relates to a wood planing machine, more particularly to a wood planing machine with an air duct for guiding air to flow into a shaving passageway along different paths.
2. Description of the Related Art
FIGS. 1 to 3 illustrate a conventional wood planing machine 10. The wood planing machine 10 includes a base 11 with upstanding posts 12 disposed at the corners of the base 11 for supporting a carriage 13 thereon. A motor 14 is mounted on the carriage 13 for driving a rotary cutter 15 which is mounted on a receiving space 131 of the carriage 13. The motor 14 is provided with a ventilation outlet 141 above the rotary cutter 15. A shaving discharge member 20 is mounted on the top surface of the carriage 13, and has a discharge plate 22. The discharge plate 22 is fastened to a pair of opposite locking pieces 132 of the carriage 13 via screw means 16 that pass through through-holes 133 in the carriage 13 and through-holes 221 in the discharge plate 22. The discharge plate 22 overlies a top surface of the carriage 13 to confine therewith a shaving passageway 171, and has an opening 222 in communication with the shaving passageway 171. A guide casing 20 is disposed on the discharge plate 22, and has an air inlet 211 in communication with the ventilation outlet 141, an air outlet 212 opposite to the air inlet 211 and aligned above the opening 222 of the discharge plate 22, and an air channel 2:L3 extending thereinside from the air inlet 211 to the air outlet 212. The shaving passageway 171 has a shaving outlet 17 opposite to the rotary cutter 15.
When in operation, air flow from the ventilation outlet 141 enters into the air channel 213 via the air inlet 211, and then flows into the shaving passageway 171 via the air outlet 212 and the opening 222 of the discharge plate 22 so as to blow wood shavings toward the shaving outlet 17. Since the air flow is only guided by the channel 213 via the opening 222 of the discharge plate 22 in one direction before entering into the shaving passageway 171, it is normally insufficient to obtain uniform distribution of the air flow inside the shaving passageway 171, thereby hindering the discharge of the wood shavings. It has been found that an increase of the height in the shaving outlet 17 may improve the discharge of the wood shavings, however, such increase may arise in a safety problem as the hands of the operator can easily enter into the outlet 17 and can thus be injured during operation.